Primer Science

glb243

Does anyone know a discernable difference between "Rifle" primers and "Pistol" primers? Has anyone out there ever substituted one for the other? Has anyone ever experimented with pistol primers while working loads for a rifle? Just a little curiosity as I sit here at my re-load bench running low on CCI 200's, while eyeing my stockpile of various large pistol primers.

Rocky Raab

First, any reloading question that starts with "Has anyone ever..." has to be answered, "Yes, somebody has."

The general but correct answer to your question is that the ONLY thing Large and Small rifle/pistol primers have in common are their respective diameters. The metal cups, the priming mix (type and/or amount), and even the height can vary. Substituting a rifle for a pistol primer or vice-versa can be useful in a very few situations -- but doing it willy-nilly is fraught with hazards.

bpost

Look at the difference in height on your LR and LP primers, ALWAYS use the primer called for in your reloading manual.

http://www.jamescalhoon.com/primers_and_pressure.php

And a very good article for you.

http://www.shootingtimes.com/2011/01/04/ammunition_st_handloadingoper_200908/

glb243

Interestingly enough, I purchased a box of 'Factory-Custom' loaded 30/06 ammo with noticablely short(likely pistol) primers. After firing three rounds,considerable primer distortion was evident(flattened,pierced). Subsequently, I stripped remaining ammo and found powder charge variations in excess of 8/10 grain.I kept factory primers in the brass, and reloaded with my powder. After shooting ammo, I found no similar primer distortion.Primers had obviously moved rearward in pockets, but piercing and or flattening did not occur. I posted this topic not to condone these substitutions, I was just curious.

375H&H

bpost , thanks for the primer read , you learn something new every day [:)]

jonk

In general good info above.

I will say though that the question of not using large pistol primers in rifle loads is a bit overstated. I did this by accident once, using H414 ball powder, one known for being 'hard' to ignite.

They all went off fine with full charge loads in my Mosin Nagant and none pierced.

OTOH, using reduced loads with cast lead, sometimes a milder pistol primer is just the ticket for top accuracy; ditto on some black powder loads.

These are specific and advanced cases; I'm just illustrating there are cases where the 'absolute' isn't absolute.

Stick with what's in the manuals and you'll be fine.

perry shooter

IN MY opinion there are at least two major things to consider and I am sure many other reasons. If you are shooting a cartridge that was designed for low pressures and the cartridge head is small dictating a Fairly small bolt face. . I have a number of 22 Hornets many are original 22 Rimfire designs WINCHESTER model 43 Anschutz model 54 action" that the factory modified to 22 Hornet and others have a very small diameter Bolt like the Brno MAUSER . all of these have very little force to the firing pin hitting the primer. I have found without exception the 22 Hornet in these rifles shoot smaller groups with small pistol primers. It also may be the fact that this case only holds a small amount of powder. YMMV

Ambrose

As perry shooter posted, it was a fairly common practice to use small pistol primers in the Hornet in the search for improved accuracy. Also, FWIW, the .357 Maximum factory loads (as well as my reloads) use Remington 7 1/2 rifle primers. Having said all that; substituting rifle/pistol primers is, in general, a bad practice.

Riomouse911

Ya, go with what the loading book says regarding the primer.

High-pressure .454 Casull, and .460 and .500 S&W loads are also primered with rifle primers. You'll see a "L R" on the headstamp of the .500 Hornady case for example, which means a "Large Rifle" primer... and the .460 S&W also uses Large Rifle primers. The much older .454 Casull rounds are primed with Small Rifle primers, and some are stamped with the "S R".

243winxb

Mysteries And Misconceptions Of The All-Important Primer http://www.shootingtimes.com/2011/01/04/ammunition_st_mamotaip_200909/

Rocky Raab

Thanks, that is a GREAT article about primers, and it answers a truckload of what Allen cleverly dubs "Myth-Conceptions."

For those who don't know, Allen Jones was the Chief Ballistician at CCI/Speer for many years.

Okie743

Very good article about primers!

Few years ago I had found by expermienting that I could use small pistol primers for good accuracy instead of small rifle primers which produced erratic accuracy when using reduced loads in a single shot 223. (using 223 reduced loads for squirrel hunting and small varmits at 22 long rifle and 22 mag velocities at 30 to 50 yards and noise level similiar to 22 magnum or less and I could use my old discarded high velocity 223 brass for the low velocity loads with no issues) I also lightly crimped the low velocity loads using the lee factory crimp die for more consistent neck tension which resulted in better consistent accuracy, but the proper selection of primers resulted in correcting the majority of the erratic accuracy issues.

bpost

The 22 hornet is another cartridge that reacts favorably to small pistol primers in a supposed rifle cartridge. It is acceptable because of the low operating pressure and small charge weights of pistol type powders used in the round. I found the 22K hornet to be particularly responsive to Lil'Gun and CCI Small Pistol primers.